Mewtwo
by MTWKing
Summary: While investigating reports of the worlds greatest Pokemon Trainer in Cerulean Cave, Tanner, Rachel and Jason find themselves face to face with the Legendary Mewtwo. Tanner quickly finds himself locked in combat with arguably the worlds strongest Pokemon. Will he be able to win? Or will Mewtwo have his revenge?


**Hello! Welcome to my second story featuring my OC Pokemon Trainer, Tanner Riverton and his friends Rachel and Jason. I would recommend you read my previous story "Memories of Past Travels" if you want to get a better understanding of the main characters but it is by no means necessary to understand/enjoy this story. Enjoy!**

 **Summary: While investigating reports of the worlds greatest Pokemon Trainer in Cerulean Cave, Tanner, Rachel and Jason find themselves face to face with the Legendary Mewtwo. Tanner quickly finds himself locked in combat with arguably the worlds strongest Pokemon. Will he be able to win? Or will Mewtwo have his revenge?**

* * *

 **Mewtwo**

Route 4, Kanto Region….

"I'm telling you it was rigged!" Tanner exclaimed as he walked down Route 4 towards Cerulean City. His loyal Umbreon, who rode on his shoulder, nodded her head emphatically to show that she agreed. "Atlas should have never won fan favourite!"

"What ever you say" sarcastically said one of his travelling companions, Rachel, as she rolled her green eyes. "It's not like he finished in second place, unlike a certain trainer we know who wears a dumb red hat"

"Hey!" Tanner exclaimed as he glared at Rachel with his brown eyes. "My hat is pretty good looking!"

"Come on guys, there's no need to fight" Said Jason, the other member of the group. The older boy was used to breaking up these pointless fights between the two ten-year-olds early, because if he didn't, it could escalate to full scale yelling matches. Although, no matter how heated arguments between Tanner and Rachel would get, neither of them would turn violent. They also seemed to move on from it in matter of minutes.

Tanner, Rachel and Jason are currently heading to Cerulean City after the conclusion of the Indigo League to pick up a parcel for Professor Oak. Tanner did well for his first league. He placed in the top 8, losing out to his new most hated rival, Atlas.

"I wonder what's in the parcel we're delivering to Professor Oak" Tanner pondered a few moments after he and Rachel cooled down.

"I don't know, maybe some cool TMs to teach beautiful moves to Pokémon" Rachel sang as her eyes sparkled. "What I wouldn't do for something like that"

"I doubt it" Jason said causing the young brunette move enthusiast to frown. "I think it might be a rare pokéball like that masterball Tanner got at Silph Co. for helping them against Team Rocket or maybe a new pokédex upgrade"

"Sounds lame" Rachel commented as she tucked a strand of her brown hair behind her ear.

"You're just upset that it probably won't be a TM" Tanner spoke. "TMs are pretty boring anyways."

"What did you say?" Rachel asked as she glared at Tanner.

"And here we go again…" Jason muttered, running a hand through his light brown hair as Tanner and Rachel started to bicker again.

After an hour of walking, the group finally reached the Cerulean City Pokémon center. However, something was off, there were more trainers than usual and they all seemed to have Pokémon with serious injuries.

Tanner was about to get Professor Oak's package from Nurse Joy when a trainer suddenly burst in to the building. He seemed to be about the same age as Tanner and Rachel, he carried a Raichu in his arms.

"Help me Nurse Joy!" He yelled. "My Raichu needs help!"

"I'm on it!" Nurse Joy exclaimed as she and her Chansey quickly put the Raichu on a stretcher and ran it into the emergency room.

"What's happening here?" Jason asked no one in particular as he looked at all of the injured Pokémon.

"It's the worlds greatest Pokémon trainer." A nearby girl spoke as she held her Bulbasaur in her arms.

"Excuse me?" Jason asked as he turned to face the girl. Tanner and Rachel also looked over at her.

"There's been signs everywhere saying that the worlds greatest Pokémon trainer is in Cerulean Cave. People have come from all over to try and beat him." The girl elaborated. "But when you go in there, he uses only one Pokémon and crushes you"

Jason grabbed his chin and started to ponder what the girl said. _Worlds greatest trainer? That can't be true…_ He thought.

"That sounds horrible" Rachel said in disgust. "Luring young trainers to a cave and then beating their Pokémon like butter, its sick!"

"Which is why I'm gonna to beat him!" Tanner suddenly proclaimed, speaking for the first time since the group arrived. Tanner's proclamation caused him to receive many looks from around the centre.

"You can't be serious" Rachel deadpanned.

"I am" Tanner replied. "It's like you said. It's terrible what this guy's doing so I'm gonna teach him a lesson by beating him, so he'll stop."

"Look around you Tanner!" Rachel exclaimed. "He merciless took down all of these poor trainers without breaking a sweat. Do really think you can match up against a trainer of this calibre? Help me out Jason."

"You're gonna need to assemble your best team if you're gonna have any chance of beating this guy" Jason told Tanner, completely dismissing Rachel. "You better call Professor Oak. And tell him his parcel might be a little late while you're at it"

"Sure thing!" Tanner replied as he went to use the video phone.

"You gotta be kidding me!" Rachel sighed.

"I agree with Tanner" Jason explained to Rachel. "Someone has to stand up to this bully"

Rachel sighed again as Jason resumed his explanation.

Meanwhile, Tanner had finished his transfers with Prof. Oak, who understood the situation and had wished Tanner luck. On his way back, he was stopped.

"So, you're the one who plans on challenging this Pokémon master" said the girl from earlier.

Tanner stopped walking towards his friends and turned to face her.

"I am"

"Good luck, I'm not sure whether or not to commend your bravery or to scold your foolishness." She warned.

"Thanks?" Tanner said before continuing back to his friends.

Rachel looked like she was about to rebut something Jason said when Tanner returned.

"What are you guys waiting for? Let's go!" he exclaimed as he ran outside of the centre.

Rachel and Jason exchanged a look before following Tanner.

"So, what is your plan exactly?" Rachel asked Tanner as the group slowly approached the entrance to Cerulean Cave.

"Win" Tanner smirked.

"Umbreon!" Umbreon exclaimed in agreement.

Rachel just sighed and rolled her eyes as the group walked into the cave. The cave was dark. The cavern walls were damp, and the sound water dripping made it seem even more ominous. Jason pulled out a flash light from his backpack and shown it down the path.

"Let's get a move on" he said. "The faster we beat this guy the better, this place is giving me the creeps"

The group slowly made their way deeper and deeper into the cave. Rachel couldn't help but notice the lack of Zubat. It unnerved her. Tanner seemed to notice it too, but thought nothing of it while Jason was feeling just as unnerved as Rachel.

The path soon opened up into a massive cavern. The cavern would dwarf most of the gyms Tanner had set foot in during his Kanto journey.

"Woah" Tanner breathed as he took in the sight. "This sure is something, isn't it Umbreon?"

"Um Umbre!" Umbreon hopped off Tanner's shoulder and started to explore while not straying too far from her trainer.

"Who knew Cerulean Cave housed caverns such as this one!" Jason said as he shined his flashlight on some sparkly looking rocks. "Look at these crystals!"

"Yeah…." Rachel trailed as she suddenly saw a hooded figure standing at the other side of the cavern.

The hood figure had glowing blue eyes that felt like the pierced her soul. Rachel suddenly felt cold.

"Uh Guys…"

Tanner and Jason turned to see the figure. Tanner's gaze instantly hardened.

"Why are you here?" The hooded figure uttered menacingly. The voiced sound almost like it was coming from everyone's own head.

Tanner was the first to reply, his confidence running at an all time high.

"I'm here to beat the world greatest trainer!" he exclaimed. "He has no right bully other trainers!"

"Your confidence shall be your own downfall" The hooded figure replied. "I, the worlds greatest Pokémon trainer, will crush you like all of those before you"

"No way! I'm winning this battle!" Tanner shouted as grabbed a pokéball off his belt.

"I choose you Sandslash!"

In a flash of light, the beige ground mouse sound appeared in front of Tanner.

"Slash!" Sandslash bellowed as it bared its claws. The spikes on its back also stood up to show its readiness to battle.

The cloaked figure stepped forewords and let his cloak fall. Tanner, Rachel and Jason all gasped at what they saw. Standing before them was the ultimate Pokémon himself, Mewtwo the attempt at cloning the legendary Pokémon Mew.

"What!?" Rachel exclaimed. "The worlds greatest trainer can't be a Pokémon!"

"I am the worlds greatest Pokémon" Mewtwo replied. "So why can't I also be the worlds greatest Pokémon trainer?"

"It doesn't matter who or what you think you are! You're just a bully!" Tanner roared. "Sandslash use Rollout!"

Sandslash curled up in a ball and rolled towards Mewtwo at high speeds. Mewtwo stood his ground a reached out with an arm at the last second. Sandslash was caught in a sphere of pink psychic energy.

Without moving, Mewtwo sent Sandslash flying into the cavern roof with incredible force.

THUD!

Sandslash fell to the ground, unmoving with swirls in his eyes.

"Nice try Sandslash" Tanner gritted his teeth as he returned his fallen Pokémon back to its pokéball.

Rachel looked on in shock.

"How did Mewtwo do that?" She asked Jason.

"Mewtwo was genetically created to be the worlds strongest Pokémon." Jason replied. "Tanner might be in over his head."

Rachel solemnly nodded and looked on.

Tanner's mind was racing. His Sandslash was taken out in one move. He would have to be careful with all of his decisions from here on out. He couldn't afford to underestimate Mewtwo like how he underestimated Atlas in the Indigo League.

"Go Dratini!" Tanner exclaimed as he tossed his next pokéball in the air.

"Dratini!" The small blue dragon Pokémon exclaimed.

"How cute" Mewtwo mocked. "A shame that it will be forced to be so mercilessly beaten"

"We'll show you!" Tanner shot back. "Dratini use Extreme Speed!"

Dratini rammed into Mewtwo like it was shot out of a cannon, the dragon type moved so quickly it was barely visible. Despite being hit across the face, Mewtwo seemed unfazed.

The genetic Pokémon created a fiery blue Aura Sphere between its two hands before sending it flying at Dratini. Tanner could only look on helplessly as the attack hit his Dratini. When the smoke cleared, Dratini was still standing but it didn't look like she had much left in her.

"Quick! Use Dragon Rage!" Tanner commanded.

Dratini shot a sphere of reddish blue energy at Mewtwo, who swiftly caught the attack with his psychic energy. Mewtwo proceeded to send the attack directly back at Dratini.

"Dratini no!" Tanner cried as he watched his young Pokémon collapse to the ground.

"Poor Dratini" Rachel said as she watched Tanner return her to her pokéball.

"Tanner's starting to run out of options" Jason spoke.

Rachel looked at the older boy with interest.

"He's already lost his best physical attacker in Sandslash and his most versatile Pokémon in Dratini." He continued. "He's going to need one heck of a performance out of Charizard or Umbreon if Ivysaur and Squirtle can't do some serious damage"

"I see" Rachel replied.

"Let's go Squirtle!" Tanner yelled as he selected his next Pokémon.

The blue turtle Pokémon appeared on the battlefield ready for his trainer's command.

"Start off with Hydro Pump!" Tanner shouted.

Squirtle shot a giant torrent of water towards Mewtwo, who blocked with a shield of psychic energy.

"Don't let up! Use Skull Bash!" Tanner exclaimed once he realized that Hydro Pump was going no where fast.

"Squirt Squirtle!" Squirtle acknowledge as he tucked his head in his shell in preparation for the attack.

"Now!" Squirtle darted towards Mewtwo and slammed into it head first. Mewtwo actually reared back slightly for the first time, seemingly mildly uncomfortable. However, the genetic Pokémon still responded quickly, using a blast of psychic energy, Mewtwo sent Squirtle flying backwards towards Tanner.

Squirtle quickly jumped back on to its feet, ready for the next command.

"Strike back with Rapid Spin!" Squirtle tucked himself into his shell and charged at Mewtwo while spinning at a high velocity. Mewtwo quickly caught Squirtle in a Psychic attack and squeezed what fight was left out of the turtle Pokémon. Squirtle fell to the ground, fainted.

"Good job Squirtle" Tanner praised his fallen Pokémon as he recalled it.

The young red capped trainer turned his attention to Mewtwo.

"Why do you do this?"

"Because humanity must feel my pain" Mewtwo replied. "People should not have the right to control Pokémon! When I've finished whipping pathetic trainers like yourself, I'll beat the world's best and take over the world and free all of the Pokémon!"

"You're wrong!" Tanner yelled. "Pokémon and their trainers work together as a team! And that's why I'll beat you and save the world!"

"Go Ivysaur!"

"Saur!" Ivysaur roared as she entered the battlefield.

"Start off with a Solar Beam!" Tanner yelled. Ivysaur spent a moment to charge before unleashing a beam of solar energy out of the tip of the flower on her back. The beam struck Mewtwo in the chest. However, Mewtwo was quick to recover.

"You will lose!" Mewtwo yelled as he lifted Ivysaur in the air with psychic energy, much like what happened to Sandslash, Ivysaur was slammed into the celling before plummeting back to the cavern floor.

"Come on Ivysaur! I know you can do it!" Tanner called in support as Ivysaur began to try and stand.

"Umbre Umbreon!" Umbreon exclaimed, also in support.

"Vy Saur!" Ivysaur exclaimed as she, with much struggle, was once again able to stand.

"Awesome! Now use Razor Leaf!" Tanner shouted. Ivysaur shot a barrage of razor sharp leaves towards Mewtwo, who ate the attack like it was nothing. Mewtwo promptly responded by launching a devastating aura sphere that subsequently ended the battle for Ivysaur.

"You gave it your all and that's all I could ever ask" Tanner said as he returned Ivysaur.

Tanner narrowed his eyebrows. _Only Charizard and Umbreon left… I gotta win…._ Tanner was shaken from his thoughts by Umbreon's call. He looked down to his partner staring back at him with determination.

"Alright Umbreon! Let's go!" Tanner exclaimed as Umbreon ran in front of him, onto the battlefield.

"Use Dark Pulse!" Tanner commanded. Umbreon unleashed a beam of dark, black and purple energy. Mewtwo took what should have been a super effective surprisingly well. An Aura Sphere was quickly launched in response.

"Use Quick Attack to dodge and the use Swift!" Umbreon was barely able to dodge the oncoming attack before attacking Mewtwo with a barrage of stars. Mewtwo quickly fought back and lifted a boulder with its psychic powers and threw it at Umbreon, hitting on target. Umbreon did her best to fight through the attack and be ready for her next move.

"Get in close with Quick Attack and use Zap Cannon!" Umbreon quickly shook of the attack and obeyed her trainer's command. The moonlight Pokémon darted in to close quarters with Mewtwo and shot a powerful electric beam at it. Mewtwo shrieked out in pain before it swatted Umbreon away with a devastating Dragon Tail. Umbreon lay on her side in the middle in of the cave clearly in pain.

Mewtwo once again lifted an even larger boulder and sent it flying towards Umbreon.

"Block with Iron Tail!" Tanner exclaimed. Umbreon quickly got up and smashed the boulder into pieces with her tail as turned to look metallic like.

"Use Dark Pulse!" Umbreon launched another beam of dark energy towards the genetic Pokémon.

"Enough!" Mewtwo roared as he unleashed a Hyper Beam. The beam of pure energy sliced clean through Umbreon's Dark Pulse and hit her head on.

Umbreon collapsed unable to battle.

"You fought well" Tanner said as he recalled Umbreon to her pokéball.

Tanner twisted his hat backwards as he reached for his final pokéball.

"Charizard! I choose you!" Tanner yelled as he threw it into the air.

"Rawr!" Roared the winged fire lizard as it entered the battlefield. Charizard shot a Flamethrower in the air as show of strength.

"I'll make quick work of this and then you'll have nothing!" Mewtwo taunted. Tanner ignored that comment and called Charizard's first move.

"Quick Charizard! Use Flamethrower!" He exclaimed. Charizard shot a blast a fire at Mewtwo, hitting head on. The genetic Pokémon appeared to have completely shrugged off the attack.

Mewtwo charged an Aura Sphere that he launched at Charizard. The winged lizard did its best to shake of the attack, but, you could see he was clearly in pain.

"Now use Flare Blitz!" Charizard was cloaked in blue flames as he charged towards his opponent. As they collided, Mewtwo was slammed into the back wall of the cave causing the cavern to rumble as Charizard made contact. Mewtwo grunted as he pried himself off the wall. With a flick of his wrist, Mewtwo shot a Psycho Cut attack.

The blade of pink psychic energy collided with Charizard.

"Don't let up! Use Flamethrower!" Charizard sent a jet of flames out of his mouth that Mewtwo quickly block with a Protect.

"Quick! Try Flamethrower again!" Tanner exclaimed. Charizard quickly repositioned before firing another powerful flamethrower. Mewtwo launched an Aura Sphere that collided with Charizard's attack causing a small explosion to erupt.

"Tanner's Charizard sure is something" Rachel said in awe of the clash she was watching. "He's going blow for blow with Mewtwo"

"True, but Charizard is starting to tire" Jason interjected as Charizard and Mewtwo continued to trade attacks. "Mewtwo seems to still have an awful lot left. Tanner will have to end this quick or he doesn't stand a chance"

"This will end it!" Mewtwo roared as he launched a massive Hyper Beam towards Charizard.

"Blast Burn Charizard!" Tanner countered.

Each Pokémon's most powerful attack collided in the centre of the cave. The resulting explosion rocked the cave causing some stalactites to fall from the roof. When the smoke cleared, Both Pokémon still stood staring the other down.

Tanner realized that unless he did something soon he was going to lose this battle. Charizard was clearly starting to tire while Mewtwo seemingly had energy to burn.

 _That's it!_ Tanner thought, the masterball he carried in backpack started to feel heavier. _If I can't beat Mewtwo, I'll catch it!_

"Use Blast Burn Again!" Tanner shouted, causing not just Rachel and Jason to look at him in shock but also Mewtwo.

Both of Tanner's travelling companions could not believe what they heard. Has Tanner gone crazy? There's no way Charizard could manage back to back Blast Burns.

Charizard once again unleashed a vortex of fire towards Mewtwo. The genetic Pokémon's concentration was only on Charizard. He was likely preparing a counter attack.

Tanner slipped the masterball into his hand as he recognized Mewtwo's distraction with Charizard's impending attack. Mewtwo was just about to unleash a Hyper Beam when Tanner made his move.

"Go Masterball!" he yelled as he threw the purple pokéball that never fails at Mewtwo.

"NOOOOOO!" Mewtwo screamed as the masterball slammed into his side and bounced into the air. The genetic Pokémon was sucked into the device as it opened. The masterball closed and fell to the ground and began to shake with the centre button flashing red.

Tanner stared at it intently while Rachel had her hands over mouth in shock. Jason was wide eyed and Charizard mimicked his trainer's stare.

1…

Jason's eyes started to burn the longer he stared.

2…

Charizard fell to his knees, firing back to back blast burns had taken their toll on the mighty fire type.

3….

Rachel gulped in anticipation.

Ping!

Tanner let out a sigh of relief. Not even the great Mewtwo could escape the power of the masterball. He slowly walked towards the capture device, almost scared that Mewtwo could breakout at any given moment.

Everyone held their breath as Tanner slowly reached forwards and grabbed the masterball. The red capped trainer held it in his palm as he looked at.

"Char?" Charizard was the first to speak.

"It's over buddy, well done" Tanner smiled as he faced his starter.

"Take a long rest, you deserve it" Tanner said as he recalled Charizard to his pokéball.

"Wow!" Rachel exclaimed as she ran up to Tanner. "You caught Mewtwo!"

"I'm sure not how much of it was me" Tanner rubbed the back of his head clearly embarrassed.

"But it was your quick thinking that allowed you to even try to use the masterball" Jason said as he placed a hand on Tanner's shoulder. "Most other trainers would've never thought of trying to capture Mewtwo. Of course, having the masterball helped but it was really all you"

"I guess you're right. Thanks Jason" Tanner smiled at who he considers to be his mentor.

"But now what are you gonna do with Mewtwo?" Rachel asked, shuddering at thought of encountering it again.

"I'm not sure" Tanner spoke truthfully as he clipped the masterball to his belt. "I'm gonna talk to Aunt Cassidy and Professor Oak about it first"

Tanner meant it. He had possibly captured the most powerful Pokémon in the world. He was gonna need guidance from his aunt who raised him and arguably the most knowledgeable Pokémon professor in the world. Plus, Aunt Cassidy made him promise to come to her for guidance should he ever needed it.

"Makes sense" Jason replied. "We should probably head back to Cerulean City, so Nurse Joy can look at your Pokémon."

"You don't have to tell me twice!" Rachel said as she turned to leave. "This place gives the creeps"

"Plus, we still need to get Professor Oak his parcel" Jason chuckled as he followed Rachel towards the exit of Cerulean Cave.

Tanner lingered for a few moments. He turned to look back at the sight of what might have been his biggest battle yet. He smiled as he turned to follow his friends towards their next adventure.

* * *

 **Thanks for reading! Stay tuned for more stories featuring these OCs if you enjoyed this one!**


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